CSV Parser - Empty values

[Ahsan A.]

Hi,

I'm new to flex & Bison, and I'm trying to write a csv
parser. My question is regarding the lexical scanner:

In a .csv file, if there is line:

one,two,,,three,four,"data,with comma"

I wish to return an EMPTYDATA_TOK if an empty value is
encountered (2 commas without any data in between)

the patterns are:

,          {return DELIMETER_TOK;}
\"         {return STRDELIMETER_TOK;}
\n         {return NEWLINE_TOK;}
[a-zA-Z0-9]*  {return DATATOK;}

What I wish to do is return an EMPTYTOK, when an empty
value (between two commas ) is matched. 

Since there is no way to match a null value in regex,
is there any other way I could do this ? I tried
declaring two variables int del_start, del_end, and
checking for an empty value in between 2 commas, and
returning an EMPTYTOK, but in that case I need TWO
return statements in one action... which is not
possible...

The bison grammar is fairly simple...

Or would you recommend I write a scanner of my own for
this ? The object of writing this parser is to flex my
knowledge of GNU flex. :)

Regards,

Ahsan

__________________________________________________
Do you Yahoo!?
Yahoo! Shopping - Send Flowers for Valentine's Day
http://shopping.yahoo.com